Thanks all of you for you help. After a lot of tests I decided that for this animation I didn’t want shadows, mainly because the majority either had black backgrounds or they were far from the background (water or a map). Anyhow, I also wanted the cartoon look more like hand drawn old fashioned cartoons flat on background. Thus I didn’t want to add gradients like is often used on vector animations.
Your tips however will come to use on my future animations!
I will be uploading a demo reel to the demo section, containing clips from this and another animation.
Thanks!